Technical Field
The present invention relates to an engine automatic stop/restart device which automatically stops an engine when a predetermined engine automatic stop condition is established, and then restarts the engine when a restart condition is established.
Background Art
In a conventional art, in order to improve fuel efficiency of a vehicle or to reduce an environment load, there is a developed engine automatic stop/restart system, so-called an idling stop control system, in which an engine is automatically stopped when a predetermined condition for stopping an engine, for example, a brake-on operation or the like in a state where a vehicle speed is lower than a predetermined value, is established by an operation of a driver, and the engine is automatically restarted when a predetermined condition for restarting the engine, for example, a brake-release operation or an accelerator-press operation, is established by an operation of the driver.
In the conventional idling stop control system, just after an automatic stop requirement is caused, fuel is cut, whereby a restart requirement is caused at a halfway process in which an engine revolution number is decreased. However, in this case, when an engine is cranked and restarted by energizing a starter after the engine is completely stopped, a long time is required after an automatic stop requirement is caused until the engine is completely restarted, so that there is a case in which a driver feels a delay time (time lag) of a restarting operation.
Therefore, there is a developed technology in which a ring gear and a pinion gear are engaged so as to restart an engine when an engagement-permission condition of the ring gear and the pinion gear is established and an engine-restart condition is established at a halfway process in which an engine revolution number is decreased by a fuel cut operation of an idling-stop control (for example, refer to Patent Document 1).
In the conventional device which is disclosed in Patent Document 1, when an engine revolution number Ne is higher than a second predetermined revolution number, an engagement-prohibition condition is not established. Moreover, when the engine revolution number Ne is lower than or equal to a first predetermined revolution number and an engagement-permission condition is established, it is judged that a revolution number for engaging the ring gear and the pinion gear is set within a defined revolution number difference range (−150 rpm˜150 rpm), and a solenoid is energized by a start control means, and the pinion gear is pushed, and an impact, which is caused when the ring gear and the pinion gear are engaged, is reduced, whereby a restart operation of the engine, which is idling, in an automatic idling stop system can be immediately and quietly performed.
In this case, the second predetermined revolution number is defined as an engine revolution number at a timing which is backed in a delay time Td, which is a time after the solenoid is energized until the engagement of the gears is completed, from a time when the engine revolution number is equal to the engagement-allowable-range-lower-limit revolution number, and the first predetermined revolution number is defined as an engine revolution number at a timing which is backed in the delay time Td, which is the time after the solenoid is energized until the engagement of the gears is completed, from a time when the engine revolution number is equal to the engagement-allowable-range-upper-limit revolution number.